Japanese Patent Application Publication No. 2005416963 discloses a switching device having a semiconductor substrate, an upper surface of which is connected to a heat sink block by soldering.
Further, Japanese Patent Application Publication No. 2015-225872 discloses a switching device having a trench that extends in a grid shape in an upper surface of a semiconductor substrate. The trench that extends in the grid shape includes a plurality of first trenches and a plurality of second trenches. The first trenches extend parallel to each other along a certain direction. The plurality of second trenches is provided in each inter-trench region interposed between the first trenches. Each second trench is connected to the first trenches on its both sides. Inner surfaces of the first trenches and inner surfaces of the second trenches are covered with a gate insulating film. A gate electrode is disposed across inner portions of the first trenches and inner portions of the second trenches. An interlayer insulating film covers the upper surface of the semiconductor substrate and the gate electrode. A contact hole is provided in the interlayer insulating film on an upper portion of each of rectangular regions (hereinafter referred to as a cell region) surrounded by the first trenches and the second trenches in the semiconductor substrate. An upper electrode covers the interlayer insulating film, and is in contact with the semiconductor substrate in the contact holes. Each cell region includes a first region (emitter region) of a first conductivity type (n-type), and a body region of a second conductivity type (p-type). Each of the first regions is in contact with the upper electrode and the gate insulating film. The body region is in contact with the upper electrode, and is in contact with the gate insulating film below the first regions. Further, the semiconductor substrate includes a second region (drift region) of the first conductivity type. The second region is in contact with the gate insulating film below the body region, and is separated from the first regions by the body region. In this switching device, when a potential of the gate electrode is controlled to a predetermined potential, channels are formed in the body region. The first regions and the second region are electrically connected by the channels. Accordingly, a current flows between the first regions and the second region.